The invention relates to a method of manufacturing optical fiber ribbons, in which optical fibers are paid out by an optical fiber pay-out unit, and they are grouped together in a nozzle where they are coated in a coating material which is caused to set in order to form an optical fiber ribbon.
In known manner, with such a manufacturing method, where a single ribbon is manufactured, the optical fibers are paid out by reels rotatably mounted on a feed unit. They are then guided by a pulley, and grouped together parallel to one another in a nozzle, the nozzle itself being fed with a coating material which is deposited around the fibers, thereby forming a continuous layer. The coated fibers then travel through a chamber designed to cause the coating material to set and thus form a ribbon which is taken up on a take-up unit by means of a capstan.
The ribbons are used in cables which present many advantages over cables having independent or braided optical fibers, among which should be mentioned: a higher density of optical fibers; and connection operations facilitated by the fibers being in an organized disposition relative to one another.
Increasing production capacity for this type of cable is an important industrial objective. Economically, it might appear advantageous to increase the travel speed of the optical fibers during manufacture. However, the mechanical inertia of the reels, of the pulley which guides the optical fibers, and of the capstan, together with the vibrations of the optical fibers along the length of their path, put a limit on how far speed can be increased. The solution consisting in multiplying the number of installations performing the method in parallel, in order to manufacture a plurality of ribbons, is technically possible, but it presents numerous economic drawbacks, including high investment cost, and large floor space requirements.
The object of the invention is to provide a method of simultaneously manufacturing a plurality of ribbons of optical fiber in parallel, at a manufacturing cost per ribbon that is less than that which would result from merely multiplying the number of manufacturing installations.
To this end, the invention provides a method of manufacturing optical fiber ribbons, in which optical fibers are paid out by an optical fiber pay-out unit, and they are grouped together in a nozzle where they are coated in a coating material which is caused to set in order to form an optical fiber ribbon, wherein a plurality of groups of optical fibers are formed in parallel in as many nozzles, and wherein the groups of optical fibers, which are coated in a coating material, are caused to set simultaneously using a single setting means for setting the coating material, in order to form as many optical fiber ribbons.
The energy required to set the coating material is delivered simultaneously to the ribbons being manufactured in parallel. Since the setting step is the most costly step of the manufacturing method, the method of the invention allows the energy cost per ribbon to be minimized.
The floor space required is not significantly greater than that required for a single-ribbon method, insofar as the same setting means is used in common for manufacturing the ribbons.